Minimally invasive surgery (MIS) procedures avoid open invasive surgery in favor of closed or local surgery with less trauma. Minimally invasive surgical procedures typically involve remote manipulation of instruments with indirect observation of the surgical field through an endoscope or similar device, and are carried out through a small access port through the skin or through a body cavity or anatomical opening. Minimally invasive medical techniques thereby reduce tissue damage during diagnostic or surgical procedures, thereby reducing patient recovery time, discomfort, and deleterious side effects. Minimally invasive medical techniques consequently shorten the average length of a hospital stay for a procedure when compared to standard open surgery.
One form of minimally invasive surgery is endoscopy. Probably the most common form of endoscopy is laparoscopy, which is minimally invasive inspection and surgery inside the abdominal cavity. In standard laparoscopic surgery, a patient's abdomen is insufflated with gas, and cannula sleeves are passed through small (approximately ½ inch) incisions to provide access ports for laparoscopic surgical instruments. The laparoscopic surgical instruments generally include an endoscope for visualizing the surgical field and specialized surgical instruments which is, in some embodiments, passed through the access ports. The instruments can include clamps, graspers, scissors, staplers, and needle holders, for example. The surgical instruments may or may not be similar to those used in conventional (open) surgery; typically that the working end of each instrument is separated from its handle by an elongated shaft and is sized and configured to fit through the access port. To perform surgical procedures, the surgeon passes the surgical instruments through the access ports to an internal surgical site and manipulates them from outside the abdomen. The surgeon monitors the procedure by means of a monitor that displays an image of the surgical site taken from the laparoscope. Similar endoscopic techniques are employed in, e.g., arthroscopy, thoracoscopy, retroperitoneoscopy, pelviscopy, nephroscopy, cystoscopy, cisternoscopy, sinoscopy, hysteroscopy, urethroscopy, craniotomy, and natural orifice surgery (for example of the airway and gastrointestinal tract).
There are many disadvantages relating to MIS technology utilizing hand-operated instruments. For example, existing MIS instruments deny the surgeon the flexibility of instrument placement found in open surgery. Most current laparoscopic instruments have rigid shafts, so that it can be difficult to approach the surgical site through the small incision. Additionally, the length and construction of many endoscopic instruments reduces the surgeon's ability to feel forces exerted by the instrument on tissues and organs at the surgical site. The lack of dexterity and sensitivity of endoscopic instruments is an impediment to the expansion of minimally invasive surgery.
Minimally invasive telesurgery systems have been developed to increase a surgeon's dexterity when working within an internal surgical site, as well as to allow a surgeon to operate on a patient from a remote location. In a telesurgery system, the surgeon is provided with an image of the surgical site as with endoscopy. However, rather than manipulating the surgical instruments directly, the surgeon performs the surgical procedures on the patient by manipulating master input or control devices at a console. The master input and control devices control the motion of surgical instruments utilizing telemanipulators. Depending on the system, telesurgery systems may overcome some but not all of the lack of dexterity and sensitivity of endoscopic instruments. Surgical telemanipulator systems are often referred to as robotic or robotically-assisted surgery systems.
Many MIS procedures including MIS telesurgery procedures employ wound closure devices such as sutures, staples and tacks for closing wounds, repairing traumatic injuries or defects, joining tissues together (bringing severed tissues into approximation, closing an anatomical space, affixing single or multiple tissue layers together, creating an anastomosis between two hollow/luminal structures, adjoining tissues, attaching or reattaching tissues to their proper anatomical location), attaching foreign elements to tissues (affixing medical implants, devices, prostheses and other functional or supportive devices), and for repositioning tissues to new anatomical locations (repairs, tissue elevations, tissue grafting and related procedures) to name but a few examples. Sutures typically consist of a filamentous suture thread attached to a needle with a sharp point. Suture threads can be made from a wide variety of materials including bioabsorbable (i.e., that break down completely in the body over time), or non-absorbable (permanent; non-degradable) materials. Absorbable sutures have been found to be particularly useful in situations where suture removal might jeopardize the repair or where the natural healing process renders the support provided by the suture material unnecessary after wound healing has been completed; as in, for example, completing an uncomplicated skin closure. Non-degradable (non-absorbable) sutures are used in wounds where healing is, in some embodiments, expected to be protracted or where the suture material is needed to provide physical support to the wound for long periods of time; as in, for example, deep tissue repairs, high tension wounds, many orthopedic repairs and some types of surgical anastomosis. Also, a wide variety of surgical needles are available, and the shape, and size of the needle body and the configuration of the needle tip is typically selected based upon the needs of the particular application.
To use an ordinary suture, the suture needle is advanced through the desired tissue on one side of the wound and then through the adjacent side of the wound. The suture is then formed into a “loop” which is completed by tying a knot in the suture to hold the wound closed. Knot tying takes time and causes a range of complications, including, but not limited to (i) spitting (a condition where the suture, usually a knot) pushes through the skin after a subcutaneous closure), (ii) infection (bacteria are often able to attach and grow in the spaces created by a knot), (iii) bulk/mass (a significant amount of suture material left in a wound is the portion that comprises the knot), (iv) slippage (knots can slip or come untied), and (v) irritation (knots serve as a bulk “foreign body” in a wound). Suture loops associated with knot tying may lead to ischemia (knots can create tension points that can strangulate tissue and limit blood flow to the region) and increased risk of dehiscence or rupture at the surgical wound. Knot tying is also labor intensive and can comprise a significant percentage of the time spent closing a surgical wound. Additional operative procedure time is not only bad for the patient (complication rates rise with time spent under anesthesia), but it also adds to the overall cost of the operation (many surgical procedures are estimated to cost between $15 and $30 per minute of operating time). The time taken by suture tying and the range of complications is exasperated by the lack of dexterity and sensitivity of MIS instruments.
Self-retaining sutures (including barbed sutures) differ from conventional sutures in that self-retaining sutures possess numerous tissue retainers (such as barbs) which anchor the self-retaining suture into the tissue following deployment and resist movement of the suture in a direction opposite to that in which the retainers face, thereby eliminating the need to tie knots to affix adjacent tissues together (a “knotless” closure). This facilitates and expedites deployment of self-retaining sutures compared to ordinary sutures. Knotless tissue-approximating devices having barbs have been previously described in, for example, U.S. Pat. No. 5,374,268, disclosing armed anchors having barb-like projections, while suture assemblies having barbed lateral members have been described in U.S. Pat. Nos. 5,584,859 and 6,264,675. Sutures having a plurality of barbs positioned along a greater portion of the suture are described in U.S. Pat. No. 5,931,855, which discloses a unidirectional barbed suture, and U.S. Pat. No. 6,241,747, which discloses a bidirectional barbed suture. Methods and apparatus for forming barbs on sutures have been described in, for example, U.S. Pat. No. 6,848,152. It is noted that all patents, patent applications and patent publications identified throughout are incorporated herein by reference in their entirety. Self-retaining sutures result in better approximation of the wound edges, evenly distribute the tension along the length of the wound (reducing areas of tension that can break or lead to ischemia), decrease the bulk of suture material remaining in the wound (by eliminating knots) and reduce spitting (the extrusion of suture material—typically knots —through the surface of the skin. All of these features are thought to reduce scarring, improve cosmesis, and increase wound strength relative to wound closures using plain sutures or staples. Thus, self-retaining sutures, because such sutures avoid knot tying, allow patients to experience an improved clinical outcome, and also save time and costs associated with extended surgeries and follow-up treatments.